From: Sanjay Patel <spatel@rotateright.com>
Date: Wed, 17 May 2017 20:27:55 +0000 (+0000)
Subject: [InstSimplify] handle all icmp i1 X, C in one place; NFCI
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=f5276374323a68df65b4140f942c32498ee0ddeb;p=llvm

[InstSimplify] handle all icmp i1 X, C in one place; NFCI

We already handled all of the new tests identically, but several
of those went through a lot of unnecessary processing before
getting folded.

Another motivation for grouping these cases together is that
InstCombine needs a similar fold. Currently, it handles the
'not' cases inefficiently which can lead to bugs as described
in the post-commit comments of:
https://reviews.llvm.org/D32143


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@303295 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index 5652248a60c..0a056c0d086 100644
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -2260,28 +2260,49 @@ static Value *simplifyICmpOfBools(CmpInst::Predicate Pred, Value *LHS,
   if (!OpTy->getScalarType()->isIntegerTy(1))
     return nullptr;
 
-  switch (Pred) {
-  default:
-    break;
-  case ICmpInst::ICMP_EQ:
-    // X == 1 -> X
-    if (match(RHS, m_One()))
-      return LHS;
-    break;
-  case ICmpInst::ICMP_NE:
-    // X != 0 -> X
-    if (match(RHS, m_Zero()))
+  // A boolean compared to true/false can be simplified in 14 out of the 20
+  // (10 predicates * 2 constants) possible combinations. Cases not handled here
+  // require a 'not' of the LHS, so those must be transformed in InstCombine.
+  if (match(RHS, m_Zero())) {
+    switch (Pred) {
+    case CmpInst::ICMP_NE:  // X !=  0 -> X
+    case CmpInst::ICMP_UGT: // X >u  0 -> X
+    case CmpInst::ICMP_SLT: // X <s  0 -> X
       return LHS;
-    break;
-  case ICmpInst::ICMP_UGT:
-    // X >u 0 -> X
-    if (match(RHS, m_Zero()))
+
+    case CmpInst::ICMP_ULT: // X <u  0 -> false
+    case CmpInst::ICMP_SGT: // X >s  0 -> false
+      return getFalse(ITy);
+
+    case CmpInst::ICMP_UGE: // X >=u 0 -> true
+    case CmpInst::ICMP_SLE: // X <=s 0 -> true
+      return getTrue(ITy);
+
+    default: break;
+    }
+  } else if (match(RHS, m_One())) {
+    switch (Pred) {
+    case CmpInst::ICMP_EQ:  // X ==   1 -> X
+    case CmpInst::ICMP_UGE: // X >=u  1 -> X
+    case CmpInst::ICMP_SLE: // X <=s -1 -> X
       return LHS;
+
+    case CmpInst::ICMP_UGT: // X >u   1 -> false
+    case CmpInst::ICMP_SLT: // X <s  -1 -> false
+      return getFalse(ITy);
+
+    case CmpInst::ICMP_ULE: // X <=u  1 -> true
+    case CmpInst::ICMP_SGE: // X >=s -1 -> true
+      return getTrue(ITy);
+
+    default: break;
+    }
+  }
+
+  switch (Pred) {
+  default:
     break;
   case ICmpInst::ICMP_UGE:
-    // X >=u 1 -> X
-    if (match(RHS, m_One()))
-      return LHS;
     if (isImpliedCondition(RHS, LHS, Q.DL).getValueOr(false))
       return getTrue(ITy);
     break;
@@ -2296,16 +2317,6 @@ static Value *simplifyICmpOfBools(CmpInst::Predicate Pred, Value *LHS,
     if (isImpliedCondition(LHS, RHS, Q.DL).getValueOr(false))
       return getTrue(ITy);
     break;
-  case ICmpInst::ICMP_SLT:
-    // X <s 0 -> X
-    if (match(RHS, m_Zero()))
-      return LHS;
-    break;
-  case ICmpInst::ICMP_SLE:
-    // X <=s -1 -> X
-    if (match(RHS, m_One()))
-      return LHS;
-    break;
   case ICmpInst::ICMP_ULE:
     if (isImpliedCondition(LHS, RHS, Q.DL).getValueOr(false))
       return getTrue(ITy);
diff --git a/test/Transforms/InstSimplify/icmp-bool-constant.ll b/test/Transforms/InstSimplify/icmp-bool-constant.ll
new file mode 100644
index 00000000000..f711fae0a85
--- /dev/null
+++ b/test/Transforms/InstSimplify/icmp-bool-constant.ll
@@ -0,0 +1,171 @@
+; RUN: opt < %s -instsimplify -S | FileCheck %s
+
+; Test all integer predicates with bool types and true/false constants.
+; Use vectors to provide test coverage that is not duplicated in other folds.
+
+define <2 x i1> @eq_t(<2 x i1> %a) {
+; CHECK-LABEL: @eq_t(
+; CHECK-NEXT:    ret <2 x i1> %a
+;
+  %r = icmp eq <2 x i1> %a, <i1 true, i1 true>
+  ret <2 x i1> %r
+}
+
+define <2 x i1> @eq_f(<2 x i1> %a) {
+; CHECK-LABEL: @eq_f(
+; CHECK-NEXT:    [[R:%.*]] = icmp eq <2 x i1> %a, zeroinitializer
+; CHECK-NEXT:    ret <2 x i1> [[R]]
+;
+  %r = icmp eq <2 x i1> %a, <i1 false, i1 false>
+  ret <2 x i1> %r
+}
+
+define <2 x i1> @ne_t(<2 x i1> %a) {
+; CHECK-LABEL: @ne_t(
+; CHECK-NEXT:    [[R:%.*]] = icmp ne <2 x i1> %a, <i1 true, i1 true>
+; CHECK-NEXT:    ret <2 x i1> [[R]]
+;
+  %r = icmp ne <2 x i1> %a, <i1 true, i1 true>
+  ret <2 x i1> %r
+}
+
+define <2 x i1> @ne_f(<2 x i1> %a) {
+; CHECK-LABEL: @ne_f(
+; CHECK-NEXT:    ret <2 x i1> %a
+;
+  %r = icmp ne <2 x i1> %a, <i1 false, i1 false>
+  ret <2 x i1> %r
+}
+
+define <2 x i1> @ugt_t(<2 x i1> %a) {
+; CHECK-LABEL: @ugt_t(
+; CHECK-NEXT:    ret <2 x i1> zeroinitializer
+;
+  %r = icmp ugt <2 x i1> %a, <i1 true, i1 true>
+  ret <2 x i1> %r
+}
+
+define <2 x i1> @ugt_f(<2 x i1> %a) {
+; CHECK-LABEL: @ugt_f(
+; CHECK-NEXT:    ret <2 x i1> %a
+;
+  %r = icmp ugt <2 x i1> %a, <i1 false, i1 false>
+  ret <2 x i1> %r
+}
+
+define <2 x i1> @ult_t(<2 x i1> %a) {
+; CHECK-LABEL: @ult_t(
+; CHECK-NEXT:    [[R:%.*]] = icmp ult <2 x i1> %a, <i1 true, i1 true>
+; CHECK-NEXT:    ret <2 x i1> [[R]]
+;
+  %r = icmp ult <2 x i1> %a, <i1 true, i1 true>
+  ret <2 x i1> %r
+}
+
+define <2 x i1> @ult_f(<2 x i1> %a) {
+; CHECK-LABEL: @ult_f(
+; CHECK-NEXT:    ret <2 x i1> zeroinitializer
+;
+  %r = icmp ult <2 x i1> %a, <i1 false, i1 false>
+  ret <2 x i1> %r
+}
+
+define <2 x i1> @sgt_t(<2 x i1> %a) {
+; CHECK-LABEL: @sgt_t(
+; CHECK-NEXT:    [[R:%.*]] = icmp sgt <2 x i1> %a, <i1 true, i1 true>
+; CHECK-NEXT:    ret <2 x i1> [[R]]
+;
+  %r = icmp sgt <2 x i1> %a, <i1 true, i1 true>
+  ret <2 x i1> %r
+}
+
+define <2 x i1> @sgt_f(<2 x i1> %a) {
+; CHECK-LABEL: @sgt_f(
+; CHECK-NEXT:    ret <2 x i1> zeroinitializer
+;
+  %r = icmp sgt <2 x i1> %a, <i1 false, i1 false>
+  ret <2 x i1> %r
+}
+
+define <2 x i1> @slt_t(<2 x i1> %a) {
+; CHECK-LABEL: @slt_t(
+; CHECK-NEXT:    ret <2 x i1> zeroinitializer
+;
+  %r = icmp slt <2 x i1> %a, <i1 true, i1 true>
+  ret <2 x i1> %r
+}
+
+define <2 x i1> @slt_f(<2 x i1> %a) {
+; CHECK-LABEL: @slt_f(
+; CHECK-NEXT:    ret <2 x i1> %a
+;
+  %r = icmp slt <2 x i1> %a, <i1 false, i1 false>
+  ret <2 x i1> %r
+}
+
+define <2 x i1> @uge_t(<2 x i1> %a) {
+; CHECK-LABEL: @uge_t(
+; CHECK-NEXT:    ret <2 x i1> %a
+;
+  %r = icmp uge <2 x i1> %a, <i1 true, i1 true>
+  ret <2 x i1> %r
+}
+
+define <2 x i1> @uge_f(<2 x i1> %a) {
+; CHECK-LABEL: @uge_f(
+; CHECK-NEXT:    ret <2 x i1> <i1 true, i1 true>
+;
+  %r = icmp uge <2 x i1> %a, <i1 false, i1 false>
+  ret <2 x i1> %r
+}
+
+define <2 x i1> @ule_t(<2 x i1> %a) {
+; CHECK-LABEL: @ule_t(
+; CHECK-NEXT:    ret <2 x i1> <i1 true, i1 true>
+;
+  %r = icmp ule <2 x i1> %a, <i1 true, i1 true>
+  ret <2 x i1> %r
+}
+
+define <2 x i1> @ule_f(<2 x i1> %a) {
+; CHECK-LABEL: @ule_f(
+; CHECK-NEXT:    [[R:%.*]] = icmp ule <2 x i1> %a, zeroinitializer
+; CHECK-NEXT:    ret <2 x i1> [[R]]
+;
+  %r = icmp ule <2 x i1> %a, <i1 false, i1 false>
+  ret <2 x i1> %r
+}
+
+define <2 x i1> @sge_t(<2 x i1> %a) {
+; CHECK-LABEL: @sge_t(
+; CHECK-NEXT:    ret <2 x i1> <i1 true, i1 true>
+;
+  %r = icmp sge <2 x i1> %a, <i1 true, i1 true>
+  ret <2 x i1> %r
+}
+
+define <2 x i1> @sge_f(<2 x i1> %a) {
+; CHECK-LABEL: @sge_f(
+; CHECK-NEXT:    [[R:%.*]] = icmp sge <2 x i1> %a, zeroinitializer
+; CHECK-NEXT:    ret <2 x i1> [[R]]
+;
+  %r = icmp sge <2 x i1> %a, <i1 false, i1 false>
+  ret <2 x i1> %r
+}
+
+define <2 x i1> @sle_t(<2 x i1> %a) {
+; CHECK-LABEL: @sle_t(
+; CHECK-NEXT:    ret <2 x i1> %a
+;
+  %r = icmp sle <2 x i1> %a, <i1 true, i1 true>
+  ret <2 x i1> %r
+}
+
+define <2 x i1> @sle_f(<2 x i1> %a) {
+; CHECK-LABEL: @sle_f(
+; CHECK-NEXT:    ret <2 x i1> <i1 true, i1 true>
+;
+  %r = icmp sle <2 x i1> %a, <i1 false, i1 false>
+  ret <2 x i1> %r
+}
+